Abstract: A temperature control system for an electrically heated cutaneous gas sensor. A heating element is provided with heating current by a closed loop temperature control circuit. The system includes a plurality of temperature monitoring circuits which are arranged to turn off the flow of heating current if the temperature of the sensor takes on an unacceptable value. The system also includes temperature setting circuitry for applying an increased temperature setpoint signal to the temperature control circuit, for a predetermined time, to reduce the time delay between the application of the sensor to the patient and the production of usable sensor data. Timing circuitry assures that the flow of heating current is not turned off in response to normal sensor temperature transients.

Abstract: An improved method and apparatus for deplating the electrodes of cutaneous oxygen sensors. A controllable voltage source selectably establishes either a polarizing voltage or a deplating voltage between the electrodes of a cutaneous oxygen sensor, while a current sensing circuit measures the current flow therebetween. If, during the calibration of the sensor, the current flow exceeds a predetermined threshold, the apparatus initiates an operator assisted sequence of operations which deplate the electrodes and restore the gas sensor to a usable operating condition. During the performance of this sequence of operations, the apparatus carries out all steps, except those which must be performed manually by an operator.

Abstract: An improved device for determining the trend of the partial pressure of a gas, such as oxygen or carbon dioxide, which diffuses outwardly through a patient's skin. The device, such as a cutaneous gas monitor, generates over time a series of partial pressure input values that are compared to one another for determining a trend in the partial pressure. This trend is communicated to the operator of the device.

Abstract: A temperature control system for an electrically heated cutaneous gas sensor. A heating element is provided with heating current by a closed loop temperature control system. The system includes a plurality of temperature monitoring and control circuits which are arranged to turn off a switch that controls the flow of current through the heating element if the temperature of the sensor varies outside of acceptable limits. The system also includes latching circuitry for maintaining the off state of the switch after the occurrence of an out of limits condition, and circuitry for preventing the latching circuitry from being actuated during normal temperature transients.